Convert OGG to OPUS

Ogg is a wrapper and the registry lists three codecs it can carry: Vorbis, Opus and FLAC. The extension says nothing about which one is inside, and that single fact decides whether this page is useful to you or a mistake. Open one file in VLC or foobar2000 and read the codec line, or run a media inspector over the directory.

The three answers point three different ways. Vorbis: a real conversion, and the rest of this page is about it. FLAC: the file is a lossless archive copy and converting it is the first lossy encode it has ever taken, so take High quality and keep the original. Opus: the file is already what this page produces, and the next section is the one to read.

Both audio targets on this site write an Opus stream inside an Ogg container through the same encoder, so an Ogg that already holds Opus is structurally the same file as the one this page would produce. Converting it decodes the audio and encodes it again, which adds a generation of loss and buys nothing but a different extension.

Renaming costs nothing and is legal: Opus in Ogg is exactly what RFC 7845 describes, and both names are valid for it. Convention has drifted towards `.opus` for Opus and `.ogg` for Vorbis, and a good deal of software follows the convention rather than reading the stream header. When a tool refuses a file for looking wrong rather than being wrong, changing three letters is the whole fix.

It would be reasonable to assume that Opus in, Opus out could merely be repackaged without touching the audio, and some command-line tools can do exactly that. This converter cannot. A bitrate is supplied to the encoder for every compressed target, which disables the library's packet-copy shortcut, so the audio is always decoded to samples and encoded again.

The practical consequence is the one above: never run an Opus file through this page expecting a free rewrap, because it is not one. Where a bit-exact repackaging is genuinely required — remuxing a stream, changing a container without touching the samples — a command-line tool that can copy packets is the correct instrument, and saying so is more useful than pretending otherwise.

Vorbis was published in 2000 and Opus as RFC 6716 in 2012, and the twelve years show most at low bitrates. Opus at 64 kbps holds up against Vorbis at roughly 96, and at 38 kbps it stays intelligible where Vorbis is falling apart. A collection re-encoded to Opus is meaningfully smaller for the same listening experience.

That is the only thing the conversion buys. It cannot restore anything Vorbis removed, and it removes a second helping of its own — spending part of its budget describing the first encoder's artefacts rather than the recording. Convert for size, or because something downstream demands Opus specifically. Never convert a Vorbis library to Opus in the belief that the newer codec repairs the older one.

The `.ogg` extension has meant Vorbis to most people for twenty-five years because that pairing came first and nothing displaced it in the public imagination. Game assets, Wikipedia media, open-source project audio and anything exported by an older Audacity all carry it and usually do hold Vorbis.

Files produced in the last decade are less predictable. Converters, recorders, download tools and messaging exports frequently write Opus and still call the result `.ogg`, because that extension is more widely recognised by upload forms. So a directory can easily contain both, with identical names and opposite answers to the question this page asks. Inspect a sample rather than assuming from the source.

The three bands resolve inside the encoder: Small file writes 38 kbps, Balanced 64 and High quality 128. A four-minute track lands near 1.1 MB, 1.9 MB and 3.8 MB. Anyone judging by MP3 or Vorbis numbers will read 64 kbps and expect something poor, and will be wrong — that is a comfortable stereo music rate on this codec.

For a second-generation transcode the useful rule is to give the encoder more room than the arithmetic suggests, because it is working on damaged material and its own decisions compound the first encoder's. Speech and voice assets are fine at Small file. Music that started as Vorbis should have Balanced at minimum, and High quality if the collection is not going to be re-made.

Metadata usually loses something at a format boundary. Not here. Ogg carries Vorbis-style comments — a plain list of uppercase keys with text values — and the Opus stream this page writes is carried in an Ogg container using the same mechanism. Title, artist, album, date, licence and any custom field arrive spelled exactly as they were.

Embedded artwork travels as a METADATA_BLOCK_PICTURE comment at both ends, which is the standard encoding and what foobar2000, VLC, Rhythmbox and the media servers read. For a converted library that is the difference between something a music server files correctly and two thousand unknown tracks, and it is the one part of this conversion that costs nothing at all.

Opus runs on a fixed 48,000 Hz sample clock and a decoder reports that rate regardless of what the encoder was handed. A 44,100 Hz Vorbis file therefore presents as 48 kHz after conversion, and a 22,050 Hz game effect does too. This is a property of the codec rather than a setting, and there is no version of the conversion that avoids it.

No listener will hear it. It shows up in two places: a cataloguing tool that logs the technical rate from each file will disagree with the originals, and an engine mixing at a fixed rate will resample at runtime, which costs a little processor time per simultaneous voice. Where hundreds of sounds play at once, normalising the rates in the pipeline is worth more than worrying about it here.

Opus is the one audio target on this site that fetches no encoder at all — every browser implemented it for calls — and the Ogg decoder is already present on your machine for Vorbis and Opus alike. A conversion starts the moment a file lands, with nothing downloaded and nothing sent.

Files are capped at 100 MB each and a hundred can be dropped in one pass, coming back as a ZIP. Since a mixed directory is the normal case for this pair, the sensible order of work is to inspect a sample first, rename the files that are already Opus, and convert only the ones that genuinely need it — which is usually a smaller job than it looked.